1. Field of the Invention
This invention generally relates to laser scanning systems for reading indicia having portions of different light reflectivity such as bar code symbols and, more particularly, to a lightweight, multi-component, compact, scan board module for use in such systems.
2. Description of Related Art
Various optical readers and optical scanning systems have been developed heretofore to optically read bar code symbols printed on labels affixed to objects in order to identify the object by optically reading the symbol thereon. The bar code symbol itself is a coded pattern comprised of a series of bars of various widths, and spaced apart from one another to bound spaces of various widths, said bars and spaces having different light-reflecting characteristics. Such readers and systems electro-optically decoded the coded patterns to a multiple alpha-numerical digit representation descriptive of the object. Scanning systems of this general type, and components for use in such systems, have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,360,798; 4,369,361; 4,387,297; 4,593,186; 4,496,831; 4,409,470; 4,460,120; 4,607,156; 4,673,805; 4,736,095; 4,758,717; 4,760,248 and 4,806,742; as well as in U.S. patent application Ser. Nos. 196,021; 7,775; 944,848; 138,563; 148,669; 148,555; 147,708; and 193,265; all of which have been assigned to the same assignee as the instant application and are incorporated herein to show the state of the art.
As disclosed in some of the above patents and applications, a particularly advantageous embodiment of such a scanning system resided, inter alia, in optically modifying and directing a laser light beam from a hand-held head which was supported by a user; aiming the head and, in some cases, the laser beam itself at a symbol to be read; repetitively scanning the laser beam and/or the field of view of a detector across the symbol; detecting the laser light reflected off the symbol during scanning; and decoding the detected reflected light.
Another advantageous embodiment resided in mounting at least some, if not all, of the system components in a stand-alone, portable workstation supported on a countertop or like surface.
Hand-held heads and workstations typically, but not necessarily, had different housings with shapes dictated by the particular application. A gun- or flashlight-shaped housing was more suitable for some hand-held applications, whereas a box- or bell-shaped housing was more suitable for some workstation applications. In any event, each differently configured housing dictated how and which system components were mounted therein. Heretofore, such system components had been mounted on rigid support plates, brackets, optical benches, a plurality of printed circuit boards and combinations thereof. Each housing, therefore, had its own customdesigned layout of system components, which was wasteful and inefficient of engineering design time and manpower.
Another drawback of known hand-held systems involved maintaining the components in the head in an optically aligned relationship even after the head was dropped and subjected to shock. Various shock mounts have heretofore been proposed, but a problem exists when a single printed circuit board is used as an alignment fixture inside the head, because this type of board is typically thin and flexes when subjected to shock. Such flexing disturbs the optical alignment of components associated with the board.